At the end of the school year DSC decided to get rid of all its old tripods from the science area. Knowing I worked in metal they told my daughter and she duly brought them home. My initial reaction to a car load of tripods was “oh no” but as soon as I got them home I thought they could be an interesting ball. I decided on legs in rather than out  for safety, and the first one I made a Gal steel ball to sit against the legs like a core. The second form I added a turned wooden ball mounted at roughly the focus of the direction of the legs and supported it on 4 triangles  and this is quite different from the first but seems to work well..